Sealing device

Abstract

The invention provides a sealing device and a rotating component using the sealing device, wherein the sealing device is capable of achieving both low torque and high sealing performance by improving grease coated on a sealing lip or a matched component of the sealing lip. A seal ring (14) is fixed to a fixed-side member (2) of a rotating member, is in sliding contact with a rotating-side member (15), and has a seal lip that is in sliding contact with the rotating-side member (15), the sliding contact surface of the seal lip is coated with a grease, the grease contains a base oil, a thickener, and an additive, and the apparent viscosity of the grease at a shear speed of 1000 s <-1 > at 60 DEG C is 0.22 Pa * s or more.

Description

Technical Field

[0001] The present invention relates to a sealing device and a rotating component having the sealing device, and more particularly to a sealed rolling bearing having a sealing member, especially to a sealed rolling bearing supporting an axle, such as a wheel hub bearing. Background Technology

[0002] Typically, rolling bearings contain a lubricant composition such as lubricating oil or grease. Bearings containing lubricant compositions are commonly used in general applications such as automobiles and industrial equipment due to their long lifespan, lack of need for external lubrication units, and low cost. Especially in applications requiring high sealing performance, contact-type sealing devices are used to seal the bearing space by bringing the sealing lip of the sealing member into contact with the sliding surface of mating components such as raceways.

[0003] The intrusion of foreign matter such as water and mud from the outside can significantly reduce the durability (wear resistance and bearing life) of bearings. Therefore, ensuring a tight seal is crucial in sealing devices. Wear resistance of the sealing material is a primary factor in ensuring a tight seal. On the other hand, from the perspective of energy conservation and carbon neutrality, the sliding of the sealing lip requires low torque.

[0004] Previously, techniques were known for sealing lubricating grease compositions with prescribed components into hub unit bearings to prevent the introduction of external foreign matter. For example, in Patent Document 1, excellent water resistance and other properties were achieved by including a base oil, a thickener, three rust inhibitors, and an anti-wear agent.

[0005] Furthermore, techniques for applying grease to the sealing lip or its mating components to reduce sliding resistance and ensure a tight seal at the sealing lip are known. For example, Patent Document 2 describes a rolling bearing in which grease is pre-applied to one side of the front end of the sealing lip, the portion of which slides in contact with the surface of the hub ring during use. Patent Document 3 describes a rolling bearing in which grease is pre-applied to the surface of the mating component that slides in contact with the sealing lip.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5110843

[0009] Patent Document 2: Japanese Patent No. 4475055

[0010] Patent Document 3: Japanese Patent No. 4997532 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] Previously, various grease compositions have been studied for grease compositions sealed inside bearings, as in Patent Document 1 mentioned above. However, there has been almost no research on greases applied to sealing lips or their mating components. Even when research has been conducted on greases applied to sealing lips or their mating components, the research has been insufficient.

[0013] For example, in Patent Document 2 mentioned above, by studying the shape of the sealing member (the size of the sealing lip, etc.), premature peeling of the grease applied to the sealing lip was prevented. This resulted in an increase in frictional resistance and a reduction in poor sealing. However, the properties of the grease itself, which are related to frictional resistance and sealing performance, were not considered. Therefore, it is possible that increased frictional resistance and poor sealing could occur due to insufficient performance of the grease. Furthermore, in Patent Document 3 mentioned above, a reduction in rotational torque was achieved by limiting the kinematic viscosity of the grease's base oil; however, limiting only the kinematic viscosity of the base oil makes it difficult to simultaneously ensure sealing performance and reduce rotational torque.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a sealing device that can achieve both low torque and high sealing performance by improving the grease applied to the sealing lip or its mating components, and a rotating component using the sealing device.

[0015] Solution for solving the problem

[0016] The sealing device of the first embodiment of the present invention is fixed to the fixed side member of the rotating component and slides in contact with the rotating side member. It has a sealing lip that slides in contact with the rotating side member, and a grease is applied to the sliding contact surface of the sealing lip. The grease is characterized in that it comprises a base oil, a thickener, and additives, and has a shear rate of 1000 s at 60°C. －1 The apparent viscosity of the grease is above 0.22 Pa·s.

[0017] The additive is characterized in that it comprises at least one of sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents. Preferably, the sulfur-phosphorus extreme pressure agents do not contain organozinc compounds or organomolybdenum compounds.

[0018] The additive is characterized in that it contains calcium sulfonate and other metal sulfonates, and does not contain ester-based rust inhibitors.

[0019] The thickener is characterized in that it is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine.

[0020] The characteristic feature is that the base oil is composed only of synthetic hydrocarbon oil or is a mixture of synthetic hydrocarbon oil and ester oil.

[0021] The characteristic feature is that the kinematic viscosity of the base oil at 40°C is 6 mm. 2 / s~20mm 2 / s.

[0022] The additives are characterized in that they contain sulfur-phosphorus extreme pressure agents or phosphorus-based extreme pressure agents, calcium sulfonates and other metal sulfonates, and do not contain ester-based rust inhibitors. The thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine. The base oil consists only of synthetic hydrocarbon oil or a mixture of the synthetic hydrocarbon oil and ester oil, and has a kinematic viscosity of 6 mm at 40°C. 2 / s~20mm 2 / s.

[0023] The sealing device is characterized in that the sealing member is formed of nitrile rubber, and as the sealing lip, a first sealing lip, a second sealing lip and a third sealing lip are sequentially provided from the inside of the bearing space, and the sliding contact surfaces of these sealing lips are coated with the grease.

[0024] The rotating component of the present invention is characterized by using at least one sealing device of the present invention. Furthermore, it is characterized in that the rotating component is a rolling bearing. Additionally, it is characterized in that the rolling bearing is a bearing that supports the axle so that it can rotate.

[0025] The first embodiment of the sealed rolling bearing of the present invention is a sealed rolling bearing having a sealing member that seals the bearing space, is fixed to a fixed-side member, and slides in contact with a rotating-side member. The sealing member has a sealing lip that slides in contact with the rotating-side member. In the sealed rolling bearing, at least one of the sliding contact surface of the sealing lip and the sliding contact surface of the rotating-side member in which the sealing lip slides in contact is coated with grease. The grease is characterized in that it comprises a base oil, a thickener, and additives, and has a shear rate of 1000 s at 60°C. －1 The apparent viscosity of the grease is above 0.22 Pa·s.

[0026] The sealing device of the second embodiment of the present invention is fixed to the fixed side member of the rotating component and slides in contact with the rotating side member. It has a sealing lip that slides in contact with the rotating side member, and a grease is applied to the sliding contact surface of the sealing lip. The grease is characterized in that it contains a base oil, a thickener, and an additive containing at least one of sulfur-phosphorus extreme pressure agents and phosphorus extreme pressure agents, and the mixed consistency measured according to JIS K 2220 is greater than 220 and less than 260.

[0027] The additive is characterized in that it further contains calcium sulfonate and other metal sulfonates, and does not contain ester-based rust inhibitors.

[0028] The thickener is characterized in that it is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine.

[0029] The characteristic feature is that the base oil is composed only of synthetic hydrocarbon oil or is a mixture of synthetic hydrocarbon oil and ester oil.

[0030] The characteristic feature is that the kinematic viscosity of the base oil at 40°C is 6 mm. 2 / s~20mm 2 / s.

[0031] The additives are characterized in that they further contain calcium sulfonates and other metal sulfonates, and do not contain ester-based rust inhibitors; the thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component; the monoamine component is an aliphatic monoamine or an alicyclic monoamine; the base oil consists only of synthetic hydrocarbon oils or a mixture of synthetic hydrocarbon oils and ester oils; and the kinematic viscosity at 40°C is 6 mm. 2 / s~20mm 2 / s, the above mixture consistency is above 230 and below 250.

[0032] The sealing device is characterized in that the sealing member is formed of nitrile rubber, and as the sealing lip, a first sealing lip, a second sealing lip and a third sealing lip are sequentially provided from the inside of the bearing space, and the sliding contact surfaces of these sealing lips are coated with the grease.

[0033] The rotating component of the present invention is characterized by using at least one sealing device of the present invention. Furthermore, it is characterized in that the rotating component is a rolling bearing. Additionally, it is characterized in that the rolling bearing is a bearing that supports the axle so that it can rotate.

[0034] The second embodiment of the sealed rolling bearing of the present invention is a sealed rolling bearing having a sealing member that seals the bearing space, is fixed to a fixed side member, and slides in contact with a rotating side member. The sealing member has a sealing lip that slides in contact with the rotating side member. In the sealed rolling bearing, at least one of the sliding contact surface of the sealing lip and the sliding contact surface of the rotating side member in which the sealing lip slides in contact is coated with grease. The grease is characterized in that it contains a base oil, a thickener, and an additive containing at least one of a sulfur-phosphorus extreme pressure agent and a phosphorus-based extreme pressure agent, and the mixture consistency measured according to JIS K 2220 is greater than 220 and less than 260.

[0035] The effects of the invention

[0036] The sealing device of the first embodiment of the present invention has a grease applied to the sliding contact surface of the sealing lip. The grease comprises a base oil, a thickener, and additives, and is subjected to a shear rate of 1000 s at 60°C. －1 The grease has an apparent viscosity of 0.22 Pa·s or higher and is fluid under these shear conditions. Therefore, when applied to the sliding contact surface of the sealing lip, the grease is supplied to the contact portion between the sealing lip and the rotating side component (e.g., an oil slinger ring), maintaining a seal and appropriately suppressing the ingress of mud and water. Thus, a sealing device that balances low torque and high sealing performance is obtained.

[0037] The above-mentioned additives include at least one of sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents, thus easily improving the sealing performance.

[0038] The sealing device of the second embodiment of the present invention has a grease applied to the sliding contact surface of the sealing lip. The grease comprises a base oil, a thickener, and an additive comprising at least one of a sulfur-phosphorus extreme pressure agent and a phosphorus-based extreme pressure agent. The mixture consistency, measured according to JIS K 2220, is greater than 220 and less than 260. Therefore, when applied to the sliding contact surface of the sealing lip, the grease provides sufficient lubrication at the contact portion between the sealing lip and the rotating side component (e.g., an oil slinger ring), thus suppressing wear. This results in a sealing device that balances low torque and high sealing performance.

[0039] In the sealing devices of the above embodiments, the additives contain calcium sulfonates and other metal sulfonates, and do not contain ester-based rust inhibitors, thus easily improving the sealing performance.

[0040] In the sealing devices of the above embodiments, the thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component. The monoamine component is an aliphatic monoamine or an alicyclic monoamine, which further contributes to low torque.

[0041] In the sealing devices of the above embodiments, the base oil is composed only of synthetic hydrocarbon oil or a mixture of synthetic hydrocarbon oil and ester oil, which further contributes to low torque.

[0042] In the sealing devices of the above embodiments, the kinematic viscosity of the base oil at 40°C is 6 mm. 2 / s~20mm 2 / s, thus further contributing to low torque.

[0043] In the sealing devices of the above embodiments, the sealing member is formed of nitrile rubber and has multiple sealing lips as sealing lips. The sliding contact surfaces of these sealing lips are coated with grease, thus enabling further improvement in sealing performance while ensuring low torque.

[0044] The rotating component of the present invention uses at least one sealing device of the present invention, thus obtaining a rotating component that balances low torque and high sealing performance. Furthermore, since the rotating component supports the axle as a rotatable rolling bearing, it contributes to the high functionality (low fuel consumption) of axle bearings such as wheel hub bearings.

[0045] The first embodiment of the sealed rolling bearing of the present invention has at least one surface coated with grease, namely the sliding contact surface of the sealing lip and the sliding contact surface of the rotating side member in sliding contact with the sealing lip. The grease comprises a base oil, a thickener, and additives, and is subjected to a shear rate of 1000 s at 60°C. －1 The grease has an apparent viscosity of 0.22 Pa·s or higher and is fluid under these shear conditions. Therefore, when applied to the sliding contact surface of the sealing lip or the sliding contact surface of the rotating component, the grease supplied to the contact portion between the sealing lip and the rotating component (e.g., an oil slinger ring) maintains a seal and appropriately inhibits the ingress of mud and water. This results in a sealed rolling bearing that balances low torque and high sealing performance.

[0046] The second embodiment of the sealed rolling bearing of the present invention has a grease applied to at least one of the sliding contact surfaces of the sealing lip and the rotating side member in which the sealing lip slides. The grease comprises a base oil, a thickener, and an additive comprising at least one of a sulfur-phosphorus extreme pressure agent and a phosphorus-based extreme pressure agent. The mixture consistency, measured according to JIS K2220, is greater than 220 and less than 260. Therefore, when applied to the sliding contact surfaces of the sealing lip or the rotating side member, the grease provides sufficient lubrication at the contact points between the sealing lip and the rotating side member (e.g., an oil slinger ring), suppressing wear. Thus, a sealed rolling bearing that balances low torque and high sealing performance is obtained. Attached Figure Description

[0047] Figure 1 This is a longitudinal sectional view showing an example of the rotating component of the present invention.

[0048] Figure 2 It means Figure 1 An enlarged cross-sectional view of the bearing seal structure on the inner side.

[0049] Figure 3 It means Figure 1 An enlarged cross-sectional view of the bearing seal structure on the outer side.

[0050] Figure 4 This is a schematic diagram illustrating an example of a rotary rheometer.

[0051] Figure 5 This is a longitudinal sectional view showing another example of the rotating component of the present invention.

[0052] Figure 6 yes Figure 5 An enlarged sectional view of the rotating component. Detailed Implementation

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a longitudinal sectional view showing an example of a sealed rolling bearing, which is a rotating component of the present invention, namely a hub bearing. Figure 1 The hub bearing 1 shown is a bearing for supporting the axle on the side of the drive wheel that can rotate.

[0054] like Figure 1 As shown, the wheel hub bearing 1 includes: an outer member 2, which has a body mounting flange 2b integrally mounted on the outer circumference of the vehicle body (not shown), and multiple rows of outer raceway surfaces 2a, 2a formed on the inner circumference; a wheel hub ring 4, which has a wheel mounting flange 4b ​​integrally mounted on one end for mounting a wheel (not shown), and has an inner raceway surface 4a on the outer circumference facing one of the multiple rows of outer raceway surfaces 2a, 2a, and a cylindrical small-diameter stepped portion 4c extending axially from the inner raceway surface 4a, and has serrations 6 for torque transmission formed on the inner circumference; and an inner ring 5, which is pressed into the small-diameter stepped portion 4c, and has another inner raceway surface 5a formed on the outer circumference.

[0055] Multiple rows of rolling elements (balls) 7 are freely housed by a cage 8 between multiple rows of outer raceway surfaces 2a, 2a and inner raceway surfaces 4a, 5a facing the outer raceway surfaces 2a, 2a. Furthermore, a bearing sealing structure 11, 16 is constructed in the annular space formed between the inner square member 3 (consisting of the hub ring 4 and the inner ring 5, which serves as a rotating member) and the outer square member 2 (which serves as a fixed member), preventing leakage of the grease composition sealed in the bearing space 9 and preventing rainwater, dust, etc., from entering the bearing space 9 from the outside. Utilizing... Figure 2 This section describes the bearing seal 11, which is installed on the inner side (right side of the figure) between the outer member 2 and the inner ring 5 in these bearing seal structures 11 and 16.

[0056] like Figure 2As shown, the bearing sealing structure 11 includes: a sealing ring 14, which is composed of a core 12 and a sealing member 13. The core 12 is embedded in the outer member 2 and is formed in an L-shaped cross-section. The sealing member 13 is integrally vulcanized and bonded to the core 12; and an oil-slinging ring 15, which is embedded in the inner ring 5 and is also formed in an L-shaped cross-section. In the bearing sealing structure 11, the sealing ring 14 corresponds to the sealing device of the present invention. The core 12 of the oil-slinging ring 15 and the sealing ring 14 is formed by stamping austenitic stainless steel sheet (such as SUS304 series of JIS standard) or cold-rolled steel sheet (such as SPCC series of JIS standard) that has undergone rust prevention treatment.

[0057] The sealing component 13 is made of materials such as nitrile rubber (NBR), acrylic rubber, silicone rubber, or fluororubber. Figure 2 In this structure, the sealing member 13 has three sealing lips 13a, 13b, and 13c sequentially from the inside of the bearing space: an inner lip, a middle lip, and an outer lip. The leading edge of the outer sealing lip 13c slides in contact with the inner surface of the vertical plate portion 15b of the oil slinger ring 15, while the leading edges of the remaining middle sealing lip 13b and the inner sealing lip 13a slide in contact with the cylindrical portion 15a of the oil slinger ring 15. In this structure, the core rib 12 corresponds to the fixed side member, and the oil slinger ring 15 corresponds to the rotating side member.

[0058] exist Figure 2 In the structure, grease is applied to the sliding contact surface of the sealing lip of the sealing member. Specifically, such as... Figure 2 As shown, grease G is applied to the sliding contact surfaces of the sealing lips 13a, 13b, and 13c that slide in contact with the oil slinger 15. In this case, the grease G may be applied at least to the sliding contact surfaces of the sealing lips, or it may be applied to the entire sealing lip. Furthermore, the grease G has a connection with the bearing space 9 (see reference 9). Figure 1 The lubricating grease compositions have different compositions.

[0059] In this invention, the grease G (coating grease) comprises a base oil, a thickener, and additives. The grease will be described below.

[0060] [First Implementation]

[0061] In the first embodiment of the present invention, the characteristic is that the shear rate of the lubricating grease at 60°C is 1000 s. －1 The apparent viscosity of the grease applied is 0.22 Pa·s or higher. The inventors envisioned the fluidity of the grease near the sliding contact surface, focusing on a shear rate of 1000 s at 60°C during grease application. －1The apparent viscosity was determined. In-depth research revealed that by using a coating grease with an apparent viscosity of 0.22 Pa·s or higher, it was possible to maintain low torque while achieving good sealing performance in mud and water resistance tests.

[0062] In the above-mentioned grease, the apparent viscosity is preferably 0.22 Pa·s or more and 0.30 Pa·s or less, and more preferably 0.24 Pa·s or more and 0.28 Pa·s or less.

[0063] The apparent viscosity of grease can be calculated using a rheometer. A rotary rheometer with a cone-plate element is preferred. Figure 4 This describes the general outline of such a rheometer. For example... Figure 4 As shown, the rotary rheometer 21 consists of a conical plate element 22 and a horizontal disc plate 23, arranged such that the element 22 and the plate 23 are in contact at point 1 (with a small gap), and a lubricating grease 24 serving as a sample is placed between them. In this rheometer, the shear rate applied to the lubricating grease 24 is not dependent on the distance from the center of the element and is the same regardless of the location. In this invention, the temperature is 60°C and the shear rate is 1000 s. －1 Under these conditions, the shear stress at which the shear stress becomes constant (stable) is measured, and the apparent viscosity of the grease is calculated using this shear stress.

[0064] The viscosity calculations described above utilize, for example, the Herschel-Bulkley equation, a commonly used flow equation for non-Newtonian fluids. The Herschel-Bulkley equation is expressed as follows.

[0065] [Mathematical Expression 1]

[0066]

[0067] η: Viscosity [Pa·s]

[0068] τ y Yield stress [Pa]

[0069] γ: Shear rate [1 / s]

[0070] K, n: constants

[0071] Furthermore, the yield stress and constants in the above formulas can be determined based on the evaluation of the rheological properties of the grease using a rheometer.

[0072] The above-mentioned grease has a shear rate of at least 1000 s at a temperature of at least 60°C. －1 The apparent viscosity of the grease should be above 0.22 Pa·s, and it is possible to use a combination of base oil, thickener, and additives.

[0073] The base oils used in lubricating greases can be commonly used in the field of lubricating greases. Examples include paraffinic mineral oils, naphthenic mineral oils, polyalphaolefin (PAO) oils, alkylbenzene oils, alkylnaphthalene oils, polyphenyl oils, synthetic naphthenic oils, polybutene oils, and other synthetic hydrocarbon oils (non-polar oils), ester oils, ether oils, silicone oils, and fluorinated oils. These oils can be used alone or in combination of two or more.

[0074] In the above, the base oil is preferably selected from at least one of synthetic hydrocarbon oils and ester oils, and more preferably, the base oil is composed only of synthetic hydrocarbon oils or a mixture of synthetic hydrocarbon oils and ester oils. In the case of such a mixture, the synthetic hydrocarbon oil preferably accounts for 60% or more by mass of the total base oil (mixture), more preferably 65% ​​to 90% by mass.

[0075] PAO oil, as a synthetic hydrocarbon oil, is a mixture of oligomers or polymers of α-olefins or isomerized α-olefins. Specific examples of α-olefins include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetracene, 1-tetradecene, 1-pentadecanene, 1-hexadecene, 1-heptadecene, 1-heptadecene, 1-octadecene, 1-nonadecanene, 1-eicosodeene, 1-docosahexadecene, and so on, and mixtures of them are usually used.

[0076] Examples of ester oils include dibutyl sebacic acid, di(2-ethylhexyl) sebacic acid, dioctyl adipate, trioctyl trimellitate, tridecyl trimellitate, tetraoctyl pyromellitic acid, trimethylolpropane octanoate, trimethylolpropane nonanoate, pentaerythritol ester oil, carbonate oils, and phosphate ester oils. Among these, pentaerythritol ester oil is preferred.

[0077] From the perspective of reducing torque, the kinematic viscosity of the base oil used in the grease at 40°C (or the kinematic viscosity of the blended oil in the case of a mixed oil, the same applies below) is, for example, 6 mm. 2 / s~30mm 2 / s, preferably 6mm 2 / s~20mm 2 / s, more preferably 12mm 2 / s~19mm 2 / s, or 12mm 2 / s~16mm 2 / s.

[0078] Furthermore, there are no particular limitations on the thickener used in the grease; commonly used thickeners in the field of greases can be used. For example, soap-based thickeners such as metal soaps and complex metal soaps, as well as non-soap-based thickeners such as bentonite, silica gel, diurea compounds, triurea compounds, tetraurea compounds, and urea-carbamate compounds can be used. Examples of metal soaps include sodium soaps, calcium soaps, and lithium soaps; examples of complex metal soaps include complex lithium soaps. Among these, diurea compounds are preferred.

[0079] Diurea compounds are obtained by reacting a diisocyanate component with a monoamine component. Examples of diisocyanate components include phenyl diisocyanate, toluene diisocyanate, biphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexamethylene diisocyanate. Furthermore, aliphatic, alicyclic, and aromatic monoamines can be used as the monoamine component. Examples of aliphatic monoamines include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, and oleylamine. Examples of alicyclic monoamines include cyclohexylamine. Examples of aromatic monoamines include aniline and p-toluidine.

[0080] Among these diurea compounds, aromatic diisocyanates are preferred as the diisocyanate component and at least one of aliphatic and alicyclic monoamines as the monoamine component due to their superior low torque properties. More preferably, an aliphatic-alicyclic diurea compound prepared using an aromatic diisocyanate as the diisocyanate component and both aliphatic and alicyclic monoamines as the monoamine components is used as a thickener. The ratio of aliphatic to alicyclic monoamines used in the preparation of this aliphatic-alicyclic diurea compound is not particularly limited, but a molar ratio of aliphatic monoamine to alicyclic monoamine of (3:1) to (1:3) is preferred, and this molar ratio is (2:1) to (1:2). Furthermore, the number of moles of aliphatic monoamines may be greater than the number of moles of alicyclic monoamines.

[0081] The base grease using diurea compounds as thickeners is produced by reacting the aforementioned diisocyanate component with a monoamine component in a base oil.

[0082] In the above-mentioned grease, the thickener preferably contains 10% to 30% by mass relative to the total amount (100% by mass) of the base oil and the thickener, more preferably 10% to 20% by mass, and even more preferably 12% to 18% by mass. By using a relatively small amount of thickener, the proportion of base oil can be increased accordingly, making it easier to achieve low torque.

[0083] Furthermore, there are no particular limitations on the additives used in the grease, and known additives can be used. However, from the viewpoint of easily setting the viscosity characteristics to the desired range and improving sealing performance, the additives are preferably those that contain extreme pressure agents and rust inhibitors.

[0084] As extreme pressure agents, it is preferable to include at least one of sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents. Sulfur-phosphorus extreme pressure agents are extreme pressure agents containing sulfur and phosphorus atoms, such as thiophosphates, thiophosphites, zinc dialkyl dithiophosphate (ZnDTP), molybdenum dialkyl dithiophosphate (MoDTP), etc., with thiophosphates and thiophosphites being preferred. Phosphorus-based extreme pressure agents are extreme pressure agents containing phosphorus atoms (excluding sulfur-phosphorus extreme pressure agents), such as trialkyl phosphates, tricresyl phosphates, triphenyl phosphates, etc., phosphate esters, acidic phosphate esters, tricresyl phosphites, triphenyl phosphites, etc.

[0085] The content of the extreme pressure agent is, for example, 0.5% by mass or more and less than 3.0% by mass relative to the total amount of grease (100% by mass), preferably 0.5% by mass or more and less than 1.5% by mass.

[0086] As rust inhibitors, sulfonate-based rust inhibitors, ester-based rust inhibitors such as dehydrated sorbitan fatty acid esters, carboxylic acid-based rust inhibitors such as lauric acid and stearic acid, succinic acid and alkyl succinic acid, carboxylic acid salts such as fatty acids and naphthenic acids, and amine-based rust inhibitors such as cobalt, manganese, and zinc, can be used. Among these, it is preferable to use at least a sulfonate-based rust inhibitor as the rust inhibitor.

[0087] As sulfonate-based rust inhibitors, various metal salts and amine salts of alkyl aromatic sulfonic acids such as alkylbenzene sulfonic acid and alkylnaphthalene sulfonic acid, as well as petroleum-based sulfonic acids obtained by sulfonating aromatic components from petroleum distillates, can be used. Examples of metals constituting the metal salts include alkaline earth metals such as barium, calcium, and magnesium, alkali metals such as sodium, potassium, and lithium, and zinc. Examples of amines constituting the amine salts include ethylamine and trimethylamine. These sulfonate-based rust inhibitors can be used alone or in combination of two or more. Furthermore, sulfonate-based rust inhibitors can be neutral or alkaline sulfonates.

[0088] In particular, as a rust inhibitor, it is preferable to use two sulfonate-based rust inhibitors in combination. By combining two sulfonate-based rust inhibitors, compared to using one alone, it is easier to set the viscosity characteristics to the desired range, and the rust prevention performance can also be improved. Specifically, calcium sulfonate is combined with other metal sulfonates. In this case, ester-based rust inhibitors may not be required. Ester-based rust inhibitors are polyols such as dehydrated sorbitol, sorbitol, pentaerythritol, sucrose, and glycerol, and partial esters of carboxylic acids such as oleic acid and lauric acid, as well as succinic acid half-esters, etc.

[0089] The content of the above-mentioned rust inhibitor (the total amount when there are two or more) relative to the total amount of grease is, for example, 0.5% by mass or more and less than 3.0% by mass, preferably 0.5% by mass or more and less than 1.5% by mass.

[0090] In addition, the above-mentioned additives may also include antioxidants. Examples of antioxidants include amine-based antioxidants such as phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, p,p'-dioctyldiphenylamine, and N,N'-diisopropyl-p-phenylenediamine, and phenol-based antioxidants such as 2,2'-methylenebis(6-tert-butyl-4-methylphenol). These antioxidants can be used alone or in combination of two or more. It is preferable to use amine-based antioxidants as the antioxidant.

[0091] The content of the antioxidant mentioned above is, for example, 0.5% by mass or more and less than 3.0% by mass relative to the total amount of grease, preferably 0.5% by mass or more and less than 1.5% by mass.

[0092] Furthermore, known additives other than the extreme pressure agents, rust inhibitors, and antioxidants mentioned above can be added to the aforementioned grease. Moreover, it is preferable that it does not contain organozinc compounds such as ZnDTP or organomolybdenum compounds such as MoDTP.

[0093] The mixed consistency (JIS K 2220) of the grease used in this invention is, for example, in the range of 220 or more and 300 or less, preferably in the range of more than 220 and less than 260, and more preferably in the range of 230 or more and 250 or less.

[0094] In a particularly preferred embodiment of the lubricating grease, a base oil, a thickener, and additives are included, and a shear rate of 1000 s at 60°C is achieved. －1 The apparent viscosity of the grease is above 0.22 Pa·s. As an additive, it contains sulfur-phosphorus extreme pressure agents or phosphorus-based extreme pressure agents, calcium sulfonates, and other metal sulfonates, but does not contain ester-based rust inhibitors. The thickener is a diurea compound obtained by reacting diisocyanate components with monoamine components; the monoamine components are aliphatic and alicyclic monoamines. The base oil consists only of synthetic hydrocarbon oils or a mixture of synthetic hydrocarbon oils and ester oils. The kinematic viscosity at 40°C is 6 mm. 2 / s~20mm 2 / s. Furthermore, the aforementioned numerical ranges and structures can be further combined with the grease of this method.

[0095] [Second Implementation]

[0096] In a second embodiment of the present invention, the grease G (coating grease) comprises a base oil, a thickener, and specified additives, and has a mixed consistency exceeding 220 and less than 260. Because the mixed consistency of the grease falls within this range, sufficient lubrication is achieved at the contact portion between the sealing lip and the rotating side component (e.g., an oil slinger), suppressing wear on the sealing lip and thus maintaining sealing performance. Preferably, the mixed consistency of the grease is in the range of 230 or higher and 250 or lower.

[0097] The above-mentioned greases should have a consistency of at least 220 and less than 260, and can be used in combination with base oils, thickeners, and additives.

[0098] Furthermore, the type of base oil, the kinematic viscosity of the base oil at 40°C, the type of thickener, and the content (mass%) of the thickener relative to the total amount of base oil and thickener can be appropriately adopted using the structure described in the first embodiment above.

[0099] The grease of the second embodiment contains at least one extreme pressure agent selected from sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents as an additive. This easily further improves wear resistance.

[0100] Sulfur-phosphorus extreme pressure agents are extreme pressure agents containing sulfur and phosphorus atoms, such as thiophosphates, thiophosphites, zinc dialkyl dithiophosphate (ZnDTP), and molybdenum dialkyl dithiophosphate (MoDTP). Preferably, the sulfur-phosphorus extreme pressure agent does not contain organozinc compounds or organomolybdenum compounds; more preferably, thiophosphates or thiophosphites are used. Phosphorus extreme pressure agents are extreme pressure agents containing phosphorus atoms (excluding sulfur-phosphorus extreme pressure agents), such as trialkyl phosphates, tricresyl phosphates, triphenyl phosphates, acidic phosphates, tricresyl phosphites, triphenyl phosphites, and acidic phosphites.

[0101] The content of the extreme pressure agent is, for example, 0.5% by mass or more and less than 3.0% by mass relative to the total amount of grease (100% by mass), preferably 0.5% by mass or more and less than 1.5% by mass.

[0102] The additives mentioned above may also include known additives, and from the viewpoint of easily setting the mixing consistency to the desired range and improving wear resistance, it is preferable to include rust inhibitors.

[0103] As a rust inhibitor, the rust inhibitor described in the first embodiment above can be used. In particular, it is preferable to use two sulfonate-based rust inhibitors in combination. By combining two sulfonate-based rust inhibitors, compared to using only one, it is easier to set the mixture consistency to the desired range, and the rust-preventive properties can also be improved. Specifically, calcium sulfonate and other metal sulfonates are combined. In this case, ester-based rust inhibitors may not be present. Ester-based rust inhibitors are polyols such as sorbitol, pentaerythritol, sucrose, and glycerol, and partial esters of carboxylic acids such as oleic acid and lauric acid, as well as succinic acid half-esters.

[0104] The content of the above-mentioned rust inhibitor (the total amount when there are two or more) relative to the total amount of grease is, for example, 0.5% by mass or more and less than 3.0% by mass, preferably 0.5% by mass or more and less than 1.5% by mass.

[0105] In addition, the above-mentioned additives may also include antioxidants. The type and amount of antioxidants can be appropriately adopted using the structure described in the first embodiment above.

[0106] Furthermore, known additives other than the extreme pressure agents, rust inhibitors, and antioxidants mentioned above can be added to the aforementioned grease. Moreover, it is preferable that it does not contain organozinc compounds such as ZnDTP or organomolybdenum compounds such as MoDTP.

[0107] In a particularly preferred embodiment of the grease, the grease comprises a base oil, a thickener, and an additive comprising at least one of a sulfur-phosphorus extreme pressure agent and a phosphorus-based extreme pressure agent. The mixture consistency, as measured according to JIS K 2220, is 230 or higher and 250 or lower. The additive also includes calcium sulfonates and other metal sulfonates, and does not contain ester-based rust inhibitors. The thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component; the monoamine component is an aliphatic monoamine or an alicyclic monoamine. The base oil consists only of synthetic hydrocarbon oil or a mixture of synthetic hydrocarbon oil and ester oil, and the kinematic viscosity at 40°C is 6 mm. 2 / s~20mm 2 / s. Furthermore, the aforementioned numerical ranges and structures can be further combined with the grease of this method.

[0108] Below, using Figure 3The bearing sealing structure 16 will be described. The bearing sealing structure 16 consists of a core 17 and a sealing member 18. The core 17 is embedded within the outer member 2 and formed into a ring shape. The sealing member 18 is integrally vulcanized and bonded to the core 17. The bearing sealing structure 16 corresponds to the sealing device of the present invention. The core 17 is formed in the same manner as the aforementioned oil-slinging ring. The sealing member 18 is made of an elastic member such as nitrile rubber and has two side lips (dust seals) 18b and 18c and a single radial lip (grease seal) 18a, such that their respective front edges directly slide in contact with the surface of the hub ring 4, specifically with the inner base of the wheel mounting flange 4b, forming an arc-shaped sliding contact surface 19.

[0109] like Figure 3 As shown, in the bearing seal structure 16, grease G is also applied to the surfaces of each sealing lip 18a, 18b, 18c that slides in contact with the hub ring 4, specifically to one side of the front end of each sealing lip. This achieves a balance between ensuring sealing performance and reducing rotational torque.

[0110] Figure 5 This is a longitudinal sectional view showing another example of a sealed rolling bearing that is a rotating component of the present invention, namely a deep groove ball bearing. Figure 6 This is a partially enlarged view. In the rolling bearing 31, an inner ring 32 with an inner ring raceway surface on its outer circumferential surface and an outer ring 33 with an outer ring raceway surface on their inner circumferential surface are concentrically arranged, and a plurality of rolling elements 34 are arranged between the inner ring raceway surface and the outer ring raceway surface. The rolling elements 34 are held by a cage 35. In addition, sealing devices 37 are installed at the axial end openings of the inner and outer rings, and a grease composition 36 is sealed at least around the rolling elements 34. The inner ring 32, outer ring 33, and rolling elements 34 are made of ferrous metal materials, and the grease composition 36 is used for lubrication between the rolling elements 34 and the raceway surface.

[0111] like Figure 6 As shown, the sealing device 37 comprises a circular core 38 formed by stamping a cold-rolled steel sheet or the like, and a sealing member 39 integrally vulcanized and bonded to the core 38. The sealing member 39 has a main lip 39a branching into two strands at its end on the inner ring 32 side, and a dust lip 39b located outside the bearing space than the main lip 39a. A portion of the sealing member 39 is fixed to a sealing groove on the inner circumference of the end of the outer ring 33, which is a fixed-side member, and each sealing lip slides in contact with a sealing groove, the cross-section of which is approximately U-shaped, formed on the outer circumference of the end of the inner ring 32, which is a rotating-side member. Figure 6As shown, in the sealing device 37, grease G is also applied to the surfaces of each sealing lip 39a, 39b that slides in contact with the inner ring 32, specifically to one side of the front end of each sealing lip. Furthermore, this grease G has a different composition from the grease composition 36 sealed into the bearing space.

[0112] In the above Figures 5-6 In the example described, a deep groove ball bearing is shown as a sealed rolling bearing, but the sealing device of the present invention can also be used for cylindrical roller bearings, tapered roller bearings, self-aligning roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust self-aligning roller bearings, etc.

[0113] In addition, in the above Figures 1-3 as well as Figures 5-6 In the sealed rolling bearing, the grease used in this invention is pre-applied to the sliding contact surface of the sealing lip of the sealing member. However, instead of this method or other methods, the grease may also be pre-applied to the sliding contact surface of the sealing lip of the rotating side member.

[0114] The applications of the aforementioned sealed rolling bearings are not particularly limited, but they are especially suitable for low-speed rotation applications. Sealed rolling bearings are suitable for applications such as those operating at speeds of 2000 min... －1 The bearings used in the following speed range. Here, at 2000 min... －1 The following speed range refers to the main speed (steady-state speed) of the bearing under its operating conditions, which is 2000 min. －1 The following is a possible speed: 1500 min. －1 The following can also be 1000 min －1 the following.

[0115] Furthermore, the rotating component of the present invention is not limited to rolling bearings; it can be any rotating component that uses a sealing device that requires sealing.

[0116] Example

[0117] First, the greases with the compositions shown in Tables 1 and 2 were prepared. Furthermore, items 1) to 9) below Table 1 are also identical in Table 2.

[0118] The greases used in each test case were prepared as follows.

[0119] First, prepare oil phase A, which is prepared by mixing half the amount of isocyanate (4,4'-diphenylmethane diisocyanate, MDI) and base oil at 60°C, and oil phase B, which is prepared by mixing half the amount of amine and base oil at a specified temperature (room temperature to 60°C). Next, while stirring oil phase A, add oil phase B to mix, and heat at 100°C for 30 minutes (urea reaction). The completion of the reaction is confirmed by IR (infrared spectroscopy). Then, heat at 130°C for 1 hour (reaction stabilization), and slowly cool to room temperature. Afterward, homogenize the grease using a three-roll mill.

[0120] The obtained grease was used to perform the following physical property tests and experiments.

[0121] <Mixed consistency>

[0122] According to JIS K2220, the consistency of 60 mixtures of grease was determined.

[0123] <Apparent viscosity of grease>

[0124] Using a cone-plate rheometer (20 mm in diameter, 1° cone angle), the results were compared with various lubricants at a temperature of 60°C and a shear rate of 1000 s. －1 The grease was measured for 30 minutes, and the average value of the last minute was taken as the apparent viscosity of the grease. In this test, greases above 0.22 Pa·s were marked with ○ and greases below 0.22 Pa·s were marked with × and recorded in Tables 1 to 2.

[0125] <Sealing Torque Test>

[0126] Lubricating grease was applied to one side of the front end of the three sealing lips of a nitrile rubber sealing component (φ60~70mm). The sealing component was then installed on the outer ring component of a simulated wheel hub, and an SUS430 oil slinger was installed on the inner ring component of the simulated wheel hub, assembling them so that the sealing lips contacted the oil slinger. The rotational speed was set to 600 min. －1 Under ambient temperature and with the inner ring rotating, the torque (N·m) generated by the sliding contact of the sealing lip was measured for 1 minute after 30 minutes of testing. In this test, values ​​less than 0.20 N·m were marked with ○ and values ​​greater than 0.20 N·m were marked with ×, and recorded in Tables 1 to 2.

[0127] <Mud and Water Resistance Test>

[0128] Lubricating grease was applied to one side of the front end of the three sealing lips of a nitrile rubber sealing component (φ60~70mm). The sealing component was then installed on the outer ring component of a simulated wheel hub, and an oil slinger ring (SUS430) was installed on the inner ring component, assembling them so that the sealing lips contacted the oil slinger ring. A chamber was then installed on the outer surface of the oil slinger ring, and mud / water was injected, immersing the assembled sealing lips and oil slinger ring up to their lower half in the mud / water. The rotational speed was set to 1100 min. －1 The test was conducted under ambient temperature and inner ring rotation conditions, with each cycle consisting of 20 hours of operation plus 4 hours of rest. The number of cycles until mud and water entered the interior was defined as the lifespan. In this test, those with more than 25 cycles were marked with ○ and those with less than 25 cycles were marked with ×, and these results were recorded in Tables 1 and 2.

[0129] Wear Test

[0130] Lubricating grease is applied to a nitrile rubber pin (φ3mm in diameter) and a SUJ2 disc. The nitrile rubber pin is pressed against the SUJ2 disc (surface pressure 0.83MPa), mud and water are injected, and the disc is rotated for 100 minutes. －1 The wear of nitrile rubber pins was measured by testing at 80℃ for 30 minutes. In this test, wear less than 60μm was marked as ○ and wear greater than 60μm was marked as ×, and the results were recorded in Tables 1 and 2.

[0131] [Table 1]

[0132]

[0133] [Table 2]

[0134]

[0135] As shown in Table 1, the shear rate at 60℃ is 1000 s. －1 In Examples 1 to 12, where the apparent viscosity of the grease was 0.22 Pa·s or higher, both the sealing torque test and the mud and water resistance test were passed. On the other hand, in Comparative Examples 1 to 12, the sealing torque test was passed, but the shear rate at 60°C and 1000 s⁻¹ was not satisfactory. －1 The apparent viscosity of the grease was less than 0.22 Pa·s, and it failed the mud and water resistance test.

[0136] As shown above, the shearing rate at 60℃ is 1000s. －1 The grease of the first embodiment, with an apparent viscosity of 0.22 Pa·s or higher, exhibits fluidity under these shear conditions. Therefore, this grease is supplied to the contact portion between the sealing lip and the oil slinger ring, etc. As a result, it can be considered that sealing performance is maintained, and the ingress of mud and water is suppressed.

[0137] Furthermore, as shown in Table 1, in Examples 1 to 12, where the mixture consistency was greater than 220 and less than 260 (specifically, 230 or more and 250 or less), both the sealing torque test and the wear test were passed. On the other hand, in Comparative Examples 1 to 12, where the mixture consistency was 220 or less or 260 or more, the sealing torque test was passed, but the wear test was failed.

[0138] As described above, it can be considered that when the mixed consistency of the applied grease is greater than 220 and less than 260, the lubrication at the contact point between the sealing lip and the oil slinger ring is sufficient, which can suppress wear. On the other hand, when the mixed consistency is less than 220 and is relatively hard, or when the mixed consistency is more than 260 and is relatively soft, the lubrication at the contact point between the sealing lip and the oil slinger ring is insufficient, and wear is more likely to increase.

[0139] Industrial availability

[0140] The sealing device of the present invention can balance low torque and high sealing performance, and therefore can be widely used in rotating parts, such as sealed rolling bearings, and is preferably used in hub bearings where mud and water can easily enter.

[0141] Explanation of reference numerals in the attached figures

[0142] 1. Hub bearing (rotating component)

[0143] 2. External components

[0144] 3. Inner square components

[0145] 4. Wheel rims

[0146] 5 Inner Circle

[0147] 6. Serrated edges

[0148] 7. Rolling element

[0149] 8. Cage

[0150] 9. Bearing space

[0151] 11 Bearing seal structure

[0152] 12-core bone

[0153] 13 Sealing components

[0154] 14. Sealing ring (sealing device)

[0155] 15 Oil Throwing Ring

[0156] 16. Bearing sealing structure (sealing device)

[0157] 17 core bones

[0158] 18 Sealing components

[0159] 19 Sliding contact surface

[0160] 21 Rheometer

[0161] 22 Conical Plate Components

[0162] 23 Horizontal disc plate

[0163] 24. Lubricating Grease

[0164] 31 Rolling bearings (rotating components)

[0165] 32 Inner Circle

[0166] 33 Outer ring

[0167] 34 Rolling elements

[0168] 35 Cage

[0169] 36. Grease Composition

[0170] 37 Sealing device

[0171] 38 core bones

[0172] 39 Sealing components

[0173] G. Lubricating grease.

Claims

1. A sealing device, wherein the sealing device is fixed to the fixed side member of a rotating component and slides in contact with the rotating side member, wherein, The sealing device has a sealing lip that slides in contact with the rotating side member, and the sliding contact surface of the sealing lip is coated with grease, characterized in that... The grease contains base oil, thickener, and additives, and is subjected to a shear rate of 1000 s at 60°C. －1 The apparent viscosity of the grease is above 0.22 Pa·s.

2. The sealing device according to claim 1, characterized in that, The additive comprises at least one of sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents.

3. The sealing device according to claim 1, characterized in that, The additive contains calcium sulfonates and other metal sulfonates, and does not contain ester-based rust inhibitors.

4. The sealing device according to claim 1, characterized in that, The thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine.

5. The sealing device according to claim 1, characterized in that, The base oil consists only of synthetic hydrocarbon oil or is a mixture of the synthetic hydrocarbon oil and ester oil.

6. The sealing device according to claim 1, characterized in that, The kinematic viscosity of the base oil at 40°C is 6 mm. 2 / s~20mm 2 / s.

7. The sealing device according to claim 1, characterized in that, The additive contains sulfur-phosphorus extreme pressure agents or phosphorus-based extreme pressure agents, calcium sulfonates and other metal sulfonates, and does not contain ester-based rust inhibitors. The thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine. The base oil consists solely of synthetic hydrocarbon oil or is a mixture of synthetic hydrocarbon oil and ester oil, and has a kinematic viscosity of 6 mm at 40°C. 2 / s~20mm 2 / s.

8. The sealing device according to claim 1, characterized in that, The additive comprises at least one of sulfur-phosphorus extreme pressure agents and phosphorus-based extreme pressure agents, and the grease has a mixed consistency greater than 220 and less than 260 as determined according to JIS K 2220.

9. The sealing device according to claim 8, characterized in that, The additive also contains calcium sulfonates and other metal sulfonates, and does not contain ester-based rust inhibitors. The thickener is a diurea compound obtained by reacting a diisocyanate component with a monoamine component, wherein the monoamine component is an aliphatic monoamine or an alicyclic monoamine. The base oil consists solely of synthetic hydrocarbon oil or is a mixture of synthetic hydrocarbon oil and ester oil, and has a kinematic viscosity of 6 mm at 40°C. 2 / s~20mm 2 / s, wherein the mixture consistency is above 230 and below 250.

10. The sealing device according to claim 1, characterized in that, In the sealing device, the sealing member is formed of nitrile rubber and serves as the sealing lip. From the inside of the bearing space, there are a first sealing lip, a second sealing lip, and a third sealing lip in sequence, and the sliding contact surfaces of these sealing lips are coated with the lubricant.

11. A rotating component, characterized in that, Use at least one of the sealing devices described in claim 1.

12. The rotating component according to claim 11, characterized in that, The rotating component is a rolling bearing.

13. The rotating component according to claim 12, characterized in that, The rolling bearing is a bearing that supports the axle so that it can rotate.

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